A fluid flow structure for a washing machine is located within a wash tank of the washing machine, which includes a fluid flow guide surface, and a support for the guide surface. The guide surface includes at least one region contoured inconsistently from the contour of at least one corresponding wall of the washing machine wash tank. The contour of the guide surface is generally curved so as to aide in reducing and/or preventing the pinning of items that often occurs in rectangular wash tanks of the prior art. The support for the guide surface creates a gap between the guide surface and at least one wall of the washing machine wash tank.