Obtener dos imágenes aleatorias

El siguiente código nos muestra dos imágenes aleatorias del media library:

  $media_query = new WP_Query(
 array(
 'post_type' => 'attachment',
 'post_status' => 'inherit',
 'posts_per_page' => 2,
 'orderby'=>'rand'
 )
);

foreach ($media_query->posts as $post) {
 echo wp_get_attachment_image($post->ID,'thumbnail');
}