A pump assembly useful for pumping a medicament through an injection port which is removably mountable onto a patient body surface for defining a medicament injection pathway, the pump assembly including a timed pumping assembly adapted for pumping the medicament through the injection port at a given time and a removable mounting adapted for removable mounting of the timed pumping assembly onto the injection port, whereby when the timed pumping assembly is mounted onto the injection port, the medicament can be pumped by the time pumping assembly through the medicament injection pathway.