A wearable infusion pump allows a user to insert a program key into the device housing to select a continuous dosage rate. The program keys are shaped to close contacts on a printed circuit board within the housing to communicate the selected dosage to a microprocessor. In this way, a single disposable pump, sold with one SKU, can be used to deliver a plurality of dosage rates. The disposable pump is provided with on-board display and one-button on-board user operable control. In preferred embodiments, the infusion pump according to the invention may be used for the continuous delivery of insulin in the management of Type II diabetes.