call insert method with set_write_concern

docs/changelog.rst

@@ -10,6 +10,7 @@ dev
 -  Fix validation error instance in GenericEmbeddedDocumentField #1067
 -  Update cached fields when fields argument is given #1712
 -  Add a db parameter to register_connection for compatibility with connect
+-  Use insert_one, insert_many in Document.insert #1491
 -  Use new update_one, update_many on document/queryset update #1491
 -  Use insert_one, insert_many in Document.insert #1491
 

mongoengine/queryset/base.py

@@ -350,13 +350,15 @@ class BaseQuerySet(object):
                                      documents=docs, **signal_kwargs)
 
         raw = [doc.to_mongo() for doc in docs]
-        insert_func = self._collection.insert_many
+
+        with set_write_concern(self._collection, write_concern) as collection:
+            insert_func = collection.insert_many
             if return_one:
                 raw = raw[0]
-            insert_func = self._collection.insert_one
+                insert_func = collection.insert_one
 
         try:
-            inserted_result = insert_func(raw, set_write_concern(write_concern))
+            inserted_result = insert_func(raw)
             ids = return_one and [inserted_result.inserted_id] or inserted_result.inserted_ids
         except pymongo.errors.DuplicateKeyError as err:
             message = 'Could not save document (%s)'