A centrifugal compressor impeller (60; 160) has a hub (62; 162) having a gaspath surface (64; 164) extending from a leading end to a trailing end. A plurality of blades (70A, 70B; 170) extend from the hub gaspath surface and each have: a leading edge (72A, 72B; 172); a trailing edge (74A, 74B; 174); a first face (80A, 80B; 180); a second face (82A, 82B; 182); and a tip (78A, 78B; 178). A plurality of flow splitter segments (120, 122; 320, 322) extend between associated twos of the blades and each spaced from both the hub gaspath surface and the tips of the associated two blades.