RAPPs comprise a housing, a swash plate with an inclined surface, and a rotor assembly positioned adjacent the swash plate. The swash plate and/or the inclined surface are ceramic. The rotor assembly comprises a rotor-drum having at least one cylinder bore having a piston disposed therein, wherein the piston has a ball-shaped end. A slipper is interposed between the swash plate and the rotor-drum, and includes a socket joint for accommodating the piston ball-shaped end therein. A plastic material may be disposed within the socket joint. The slipper has a ceramic interface surface in contact with the inclined surface. A stator plate is positioned in the housing, and a rotor plate is interposed between the stator plate and the rotor-drum. The stator plate has a ceramic interface surface in contact with the rotor plate. The rotor plate has a ceramic interface surface in contact with the stator plate.