Insert into indexed view?
From Doc Online: 

The view referenced by table_or_view_name must be updatable and reference exactly one base table in the FROM clause of the view. 
For example, an INSERT into a multi-table view must use a column_list that references only columns from one base table. 


https://docs.microsoft.com/en-us/sql/t-sql/statements/insert-transact-sql?view=sql-server-ver15