A catheter pump assembly is provided that includes an elongate polymeric catheter body, a cannula, and a tubular interface. The elongate polymeric catheter body has a proximal end and a distal end. The cannula has an expandable portion disposed distally of the elongate polymeric catheter body. The cannula can also have another tubular portion that is proximal to the distal portion. The tubular interface has an outer surface configured to be joined to the tubular portion of the cannula and an inner surface. The inner surface is disposed over the distal end of the elongate polymeric catheter body. The tubular interface has a plurality of transverse channels extending outward from the inner surface of the tubular interface. An outer surface of the elongate polymeric catheter body projects into the transverse channels to mechanically integrate the elongate polymeric catheter body with the tubular interface.