You should be able to insert an Organization Chart "SmartArt" component into a blank PowerPoint slide. You'll have to do the WBS numbering manually, but the graphical work will be taken care of for you...
Kiron Saving Changes...
Stéphane ParentSelf Employed / Semi-retired| Leader MakerPrince Edward Island, Canada
The other option is to do a screenshot of a basic WBS in a tool such as MS Project. You can then paste it on a PowerPoint slide. Saving Changes...
You can embed an MS Excel sheet into a blank slide and then, either prepare WBS from scratch or copy paste from external file into this embedded sheet.
This will help in editing, formatting & beautifying the excel content inline within the slide.