An infusion pump (110) includes a housing (112); a rotor (230) inserted into the housing, the rotor including a first ring (38a) of surfaces (236a) that form channels with the housing, and a second ring (38b) of surfaces (236b) that form channels with the housing, the second channel forming surfaces radially offset from the first channel forming surfaces; and a motor (40) operably engaged to rotate the rotor to cause the first and second channel forming surfaces to pump a flow of fluid, the radial offsetting of the second channel forming surfaces from the first channel forming surfaces dampening a pulsatility of the flow of fluid.