An insertion mechanism for a drug pump includes an insertion mechanism housing; a sleeve; a rotational biasing member initially held in an energized state; a retraction biasing member and a hub connected to a proximal end of a needle, wherein the retraction biasing member is held initially in an energized state between the hub and the sleeve. The needle is inserted into a target tissue by the rotational biasing member and interaction between the hub and housing. Retraction of the needle is caused by decompressing or de-energizing of the retraction biasing member. A drug delivery pump includes an activation mechanism, a drive mechanism, a sterile access connection, and the insertion mechanism. Assembly and operation methods are provided.