<p>We present the kinematics of impeller wake transport along the diffuser midspan passage of an axial flow pump, based on unsteady Reynolds-averaged Navier-Stokes (URANS) simulation results. Our results share kinematic similarity with axial compressors. However, we underscore the kinematic dissimilarity that might be present due to our particular (unoptimized) diffuser blade setup, and its implication for mixing loss. After segmentation by the leading edge of the diffuser blades, an impeller wake is sequentially deformed before exiting the diffuser passage. Wake segments are compressed due to tilting, and a thick boundary layer develops on the pressure surface of the diffuser blades. Hereafter, uneven acceleration of the wake segment’s ends causes inviscid stretching. Significant hub corner separation compresses the stretched wake segment along the substantially reduced passage flow area, even in the midspan passage. This compression continues until the wake segment departs the diffuser passage. These sequential deformations from entry to exit, delay wake dissipation, albeit with the so-called inviscid wake stretching.</p>