A rotary blood pump may include one or more motor stators overlying exterior surfaces of a wall defining a pumping chamber. A rotatable impeller within the pumping chamber may have a hydrodynamic thrust bearing surface adapted to constrain a position of the impeller along an axis of rotation relative to the wall when the impeller is rotating about the axis of rotation. The impeller position may then be constrained without requiring a constant polarity magnetic force to be applied in the axial direction from a fixed position of the housing.