The pump includes a housing that forms a canister-shaped accommodation chamber with an end wall and a circumferential wall; and a pump insert is arranged in the accommodating chamber. The pump insertcomprises a rotor, a first housing portion and a second housing portion. The rotor surrounds the rotary shaft between them and is rotatably disposed relative to the first and second housing portions.A lifting ring surrounds the rotor and is disposed between the first housing portion and the second housing portion, wherein a rotation axis direction or a rotation axis direction is arranged betweenthe containing outer shell and the second outer shell part. An elastic spring is arranged in/along the rotating shaft direction, the spring has a spring structure made of metal, in particular steel; the spring structure imparts a main spring characteristic to the spring in/along the direction of the rotating shaft, and the spring is substantially supported in a region toward the second housing portion. The area is axially aligned with the lifting ring in the direction of the rotating shaft, and thus the second housing part is pressed against the lifting ring.