First go to contacts and settings/options under more and select customized display option.
Move your private contacts to either simcard contacts/or a account /phone.(Beast Option is to create a group with only the PRIVATE CONTACTS in your Gmail account)
Select only the simcard contacts/or a account /phone(Only the PRIVATE group) which has only the contacts that you want to be displayed and uncheck/hide the reset.
Now if you open whatsapp and refresh the chat contacts you will see that only your simcard contacts/or a account /phone which has only the contacts that you want are displayed and the reset are hidden.
Make sure the whatsapp-->settings-->contacts-->show hidden contacts is disabled.
WHAT ABOUT THE OTHER CONTACTS ?
Now download a third party contacts app from play store like go Contacts ex.
After installing you can select this contacts app as the default contacts app.
Here you will see all your contacts for dialing blocking phone numbers etc.
Now all the unwanted /blocked numbers will not be visible in the whatsapp chat list.
Hope this helps. Please share this to help people looking for similar issues.