Pilot of a PA-32 reported running slightly off the end of the runway when braking action was insufficient to stop on the runway.

Narrative

I had a braking action malfunction that resulted in me utilizing a small portion of grass at the end of Runway XX at ZZZ to exit the runway onto the taxiway. I could have attempted to turn off the runway at a higher than normal rate of speed; but decided that it was safer for the persons on board and the aircraft if I continued straight ahead with max available braking power that I had at the time. Therefore; the aircraft contacted the grass area for a brief period of time while exiting the runway to the taxiway. No airport signs or fences were contacted.Multiple factors contributed to this occurrence. It started with a wind shift when I was on short final for Runway XX. The wind throughout the day was switching back and forth between favoring [Runway] XX and then favoring [Runway] XY. Therefore; there were multiple times throughout the day that we switched which runway we were utilizing. This change on short final to a tail wind caused my ground speed to be higher than normal and my touchdown point to be slightly further down the runway as well. However; by the time the tail wind switched; a go-around would have been a highly risky maneuver due to the proximity and height of the trees at the departure end of the runway. When the wheels touched down; proper short field technique was utilized with flaps being retracted to 0 degrees and maximum braking applied. However; when applying the brakes; I did not have normal braking capacity. Brake pressure was normal but the plane was not de-accelerating normally. In the process of making the turn onto the taxiway; The plane slightly ventured into the grassy area on the departure end of XX. I very slowly and meticulously taxied the aircraft to parking under its own power to be disembarked and inspected. No persons were injured and no further damage was done to the aircraft or airport environment. The aircraft was parked until Maintenance could inspect the aircraft. The incident was immediately reported to the Chief Pilot; Director of Maintenance; and Director of Operations. It was suspected and confirmed when the aircraft was inspected that the brake pads had become glazed and cracked due to overheating. The rotors were confirmed to be warped as well with no flat spots confirmed on the tires but they were worn. This caused a massive depreciation in the braking availability of the aircraft. The plane was used for new hire pilot training just before this flight; so numerous short field landings were performed which caused the whole landing gear assembly to be very hot. A pre-flight inspection was performed before the flight; and all visible parts seemed to be airworthy before departure. The aircraft was fitted with all new brake pads; new brake rotors on each main; and a new tire on each main before the airplane was signed off to fly again. I performed a test flight on the aircraft the following day and the aircraft performed normally with the new parts. Four days later; the airport was swept by a street sweeper to clear the gravel and sand debris that was contaminating the airport environment. This was requested to be done before the landing incident. Many factors have been attributed to causing the incident and mitigation procedures have been implemented to reduce the risk in the future. We will ensure brakes are not being overly used so they can be used by the next crew; we will verify wind direction using the windsock on every approach; we will make sure our speeds are where they should be on approach; we will ensure that landing gear is in proper working condition on taxi-out to departure and parts are not too worn via a pre-flight inspection; and we will ensure that airport environment is being maintained free of FOD. Many landings have been completed since with no such further incident.