A catheter assembly includes a catheter body having a catheter lumen. A manifold assembly is coupled with a proximal catheter portion. A manifold lumen extends through the manifold assembly, and the manifold lumen includes an assembly cavity extending around the proximal catheter portion. A fluid jet loop is coupled with a high pressure tube at a distal catheter portion. The catheter assembly further includes a composite guide having first and second guide portions. The first guide portion includes a proximal guide insert near the proximal catheter portion, the proximal guide insert is positioned within the assembly cavity, and includes a guide insert surface flush with a catheter body interior wall. The second guide portion includes a distal guide near the distal catheter portion including a tapered loop guide surface and an intermediate guide surface of the catheter lumen flushly engaged with a leading edge of the tapered loop guide surface.
