a question about XFEM

Hellow everyone,

I've been studying XFEM method in Abaqus these days, then i want to model an inclusion problem to see the crack initiation and propagation at the interface. First i sketch a square to stand for a unit cell, then in order to assign different sections to inclusion and matrix, i cut a circle (circular inclusion) from the initial square. But when it comes to meshing, i don't know how to mesh the instance with structral quad elements independantly of the outline of the inclusion. Could anyone help me?