Flexible impeller apparatus and method

Embodiments of the invention provide an impeller assembly having a flexible impeller and a method of replacing a removable drive mechanism. The impeller assembly includes an impeller having an outer portion defining a substantially cylindrical shape, at least one flexible blade extending radially outward from the outer portion, and a first bore extending a first axial length. The impeller assembly also includes a tubular insert supported at least partially within the first bore. The tubular insert has a second bore defining a substantially cylindrical shape with a first radial distance from an axis passing through the center of the impeller, and a key portion radially extending from the second bore. The key portion defines a second radial distance from the axis larger than the first radial distance.