Abstract: A pump is disclosed, comprising: a pump block defining a cylinder in which a piston is mounted for reciprocation and positive displacement of fluids from an intake port of the pump block to a discharge port of the pump block; an intake valve located in the intake port of the pump block and a discharge valve located in the discharge port of the pump block; the intake valve having a valve plug that has a closed position in which the valve plug is seated on a valve seat in the intake port; a wear sleeve lining at least a portion of the intake port upstream of the valve seat; a pressure sensor upstream of the intake valve for detecting a pressure condition indicative of failure of the intake valve to provide a seal when the intake valve is in the closed position; and a controller responsive to the pressure sensor to send a signal to stop operation of the pump upon detection of the pressure condition.