A compressor assembly for a gas turbine engine includes rotatable impeller with forward and aft ends, including: an annular hub defining a generally concave-curved cross-sectional inner flowpath surface at its radially outer periphery, the inner flowpath surface extending between an inlet and an exit; an annular array of airfoil-shaped inducer blades extending radially outward from the inner flowpath surface near the forward end; and an annular array of exducer blades extending outward from the inner flowpath surface, the array of exducer blades axially spaced apart from the array of inducer blades; a non-rotating shroud assembly surrounding the impeller and including a convex-curved outer flowpath surface, wherein the inner and outer flowpath surfaces cooperate to define a primary flowpath past the blades and the stator vanes; and an annular array of airfoil-shaped stator vanes extending radially inward from the outer flowpath surface into a space between the inducer and exducer blades.