A multiphase pump for conveying a multiphase process fluid from a low pressure side to a high pressure side includes an outer housing, a casing, the casing having a pump inlet and a pump outlet for the process fluid, and a pump rotor capable of rotating about an axial direction arranged within the casing, and configured to convey the process fluid from the pump inlet to the pump outlet. The casing includes a plurality of stage segments, and the plurality of stage segments include an individual stage-segment, a low pressure segment arranged at the pump inlet and a high pressure segment arranged at the pump outlet, the individual stage-segment arranged between the high pressure segment and the low pressure segment, and the plurality of stage segments being held together by a sealing support structure, the casing being arranged within the outer housing.