An insertion mechanism (200) for a drug pump (10, 1300) includes an insertion mechanism (200) housing (202, 1202, 2202, 3202); a sleeve (220, 1220, 2220, 3220); a rotational biasing member (210, 1210, 2210, 3210) initially held in an energized state; a retraction biasing member (216, 1216, 2216, 3216) and a hub (212, 1212, 2212, 3212) connected to a proximal end of a needle (214, 1214, 2214, 3214), wherein the retraction biasing member (216, 1216, 2216, 3216) is held initially in an energized state between the hub (212, 1212, 2212, 3212) and the sleeve (220, 1220, 2220, 3220). The needle (214, 1214, 2214, 3214) is inserted into a target tissue by the rotational biasing member (210, 1210, 2210, 3210) and interaction between the hub (212, 1212, 2212, 3212) and housing (202, 1202, 2202, 3202). Retraction of the needle (214, 1214, 2214, 3214) is caused by decompressing or de-energizing of the retraction biasing member (216, 1216, 2216, 3216). A drug delivery pump includes an activation mechanism (14), a drive mechanism (100), a sterile access connection (300), and the insertion mechanism (200). Assembly and operation methods are provided.

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