Hi @wonderingwoman
If they're in the body of the machine there are plenty of crevices that they can crawl in and around on.
Here's a link to a [https://www.partselect.com/PS11741977-Whirlpool-WP389140-Drive-Block-2-5-16-Inch-High.htm?SourceCode=20&SearchTerm=WTW4816FW2&ModelNum=WTW4816FW2&ModelID=7606851|video] that may help.
It describes how to remove the drive block in your model washer (which is not your problem) but in doing this it shows how to remove the basket (tub).
This may give you a better view of where the bugs are.
If disassembling the machine seems too daunting, contact a reputable, professional washing machine repair service and ask for a quote.
Removing bugs can sometimes involve using poisonous chemicals but if you can get to their nest you may not have to