To review the wastage quantity that has been generated per Assembly, per Component product, you can use the Production Enquiry:
From the main menu, go to Reports, Production and select Production Enquiry.
Above the enquiry's grid layout, select Show Toolbar and click on Hidden Columns.
From the Hidden Columns pop-up window, drag and drop the "Wastage Qty" header into the grid layout.
The Production Enquiry will then populate the Wastage Quantity per component, per Assembly.
For more details on customizing grid layouts in pages, see create and manage custom grid layouts.