Pump assisted vacuum therapy impotence treatment apparatus may be provided in either electric or manually operated embodiments. The axis of a pump housing affixed to a vacuum chamber via an elastomeric coupler is at an angle to the vacuum chamber axis, and turned towards a user's torso to be drawn into the user's body for better vacuum sealing. The pump cylinder of a manual embodiment has an enlarged annular rest area for receiving a resilient skirt around the piston head during nonuse of the pump. This prevents compression set of the resilient skirt, for more reliable subsequent use of the pump. The vacuum chamber is tapered and transitions from a relatively smaller round end for receipt of a male sex organ to a relatively larger oval shaped end for bayonet mounting on the resilient coupler. A pair of sizing inserts adjusts the vacuum chamber end which receives the male sex organ. The smaller of the two inserts recesses into the larger insert, which improves the vacuum seal formed with the larger insert. The inserts help reduce scrotal tissue intake.