'AssimpImporter' should be able to import 3D models supported by 'Assimp' library, but there is no such class in Qt, at least not in Qt 5.5.1 (Kubuntu 16.04.3), Qt 5.10.0 (Windows 10 and Kubuntu 16.04.3) and Qt 5.10.1 (Windows 10).

Personally I wouldn't recommend you using Qt3D (at this point), since this module still looks like a technology preview although is not marked as such.