An external rotor pump has an outer rotor with a sliding surface which is arranged on the outer side thereof, and an opposing body in which the outer rotor is mounted rotatably by way of the sliding surface thereof on an inner guide surface of the opposing body and is in mechanical contact with the inner guide surface. An inner rotor which is mounted such that it can be rotated eccentrically with respect to the outer rotor is provided. The sliding surface or the inner guide surface has a surface structure which has a load-bearing region and a non-load-bearing region which is depressed in contrast with the former.

An external rotor pump, in particular a hydraulic external rotor pump, has a first component which is configured as an outer rotor with a sliding surface which is arranged on the outer side thereof, and a second component which is configured as an opposing body and in which the outer rotor is mounted rotatably by way of the sliding surface thereof on an inner guide surface of the opposing body and is in mechanical contact with the inner guide surface. An inner rotor which is mounted such that it can be rotated eccentrically with respect to the outer rotor is provided. One of the rotors can be driven, in order to be set into a rotational movement, and the rotors are coupled to one another such that, when the drivable rotor is driven, the other rotor is likewise set into a rotational movement as a result, in order to convey fluid from a suction region to a pressure region of the external rotor pump. The sliding surface or the guide surface has a surface structure which has a load-bearing region and a non-load-bearing region which is depressed in contrast with the former. The result is that the non-load-bearing region is saved from contact between the guide surface and the sliding surface which is mounted thereon.