An infusion medium delivery system, device and method for delivering an infusion medium to a patient-user, includes a needle inserter device and method for inserting a needle and/or cannula into a patient-user to convey the infusion medium to the patient-user. The needle inserter device and method operate to insert a needle and cannula into a patient-user's skin and automatically withdraw the needle from the patient-user, leaving the cannula in place and in fluid flow communication with a reservoir. The delivery device may include a base portion and a durable portion connectable to the base portion, and wherein the base portion can be separated from the durable portion and disposed of after one or more specified number of uses. The base portion supports the reservoir and the needle inserter device, while the durable portion supports a drive device for selectively driving the infusion medium out of the reservoir and into the needle and/or cannula.