Sub-parsec (sub-pc) binary supermassive black holes (BSBHs) should be common from galaxy mergers, yet direct evidence has been elusive. We present WFC3/IR imaging for a sample of 8 candidate sub-pc BSBHs at redshifts z~0.1-0.5, as well as cross-comparison with a sample of archival ordinary quasars. The targets were identified from ordinary quasars and kinematically offset quasars whose broad H-beta lines are significantly offset (by >~ a few hundred km/s) from the systemic redshifts. We directly test the prediction that the host galaxies of BSBHs should have a higher fraction of disturbed morphologies and younger stellar bulges (high Sersic indices) from recent interactions than those of control quasars. After careful subtraction of the central quasar light, our candidate sample shows a statistically undifferentiated average asymmetry, indicative of similar numbers of late-stage mergers. This result opens questions as to the timescale differences between host and BH mergers.