Puede utilizar el objeto Publicar:
// Create post object
$my_post = array();
$my_post['post_title'] = 'My post';
$my_post['post_content'] = 'This is my post.';
$my_post['post_status'] = 'publish';
$my_post['post_author'] = 1;
$my_post['post_category'] = array(8,39);
// Insert the post into the database
wp_insert_post( $my_post );
Más información encontrada aquí .