A pump includes a molded housing configured with a rear endbell portion to receive an armature and bearing, an intermediate motor portion to receive a motor shell and magnets arranged around the armature, and a front endbell portion to receive a diaphragm assembly having a diaphragm support plate supporting a diaphragm, the rear endbell portion, the intermediate motor portion and the front endbell portion being configured as an integrated molded housing unit, the diaphragm having two circumferential diaphragm sealing surfaces. The pump also includes an upper housing configured to assemble and couple to the molded housing so as to form a circumferential fluid-tight sealing arrangement that is configured between the front endbell portion and the upper housing on only one end of the pump.