Abstract: An efficient, cost effective eccentric bearing assembly is provided for use in a multiple piston hydraulic pump. The eccentric bearing assembly includes a roller bearing having an annular race. The race includes a groove around its outside perimeter. The groove engagably receives parti-spherical faces of a pair of opposed pistons. The parti-spherical face evenly loads the race and rollers as the race reciprocates with the eccentric. The invention avoids the use of rotating thrust bearings and instead axially supports the piston clip with stationary surfaces. Placement of the parti-spherical face or an optional conical face, at the interface between the pistons and the grooved race maintains the sliding contact point for piston intake strokes near the center of the face.