A drillable bit nozzle assembly can be used on a casing drilling bit and features a support housing preferably of the same material as the bit crown. The housing is preferably attached by welding and contains a groove for a seal and internal threads for an insert retainer. A landing shoulder for the hardened inserts allows different sizes to be inserted in the housing and retained by a hardened or carbide ring holder that engages the internal threads. The insert and the retainer are sufficiently thin walled to break during mill out while the housing is softer and easily milled out.