The inventive technology, in particular embodiments thereof, may be described as an apparatus (e.g., a pump) that imparts work to and redirects a fluid, and that features an impeller configured to contact and redirect an impeller inflow along a toroidal flowpath to generate an impeller discharge that has both axial and tangential velocity components, where the axial velocity component is substantially 180 degrees relative to a direction of an impeller inflow, in a meridional plane, the apparatus also featuring a diffuser having a diffuser axis that is aligned with an impeller axis of rotation, the diffuser featuring a diffuser outlet annular radial size that is greater than a diffuser inlet annular radial size; and/or curved diffuser vanes established as part of the diffuser, that redirect the impeller discharge so as to reduce the tangential velocity components.