I believe Wero is just a service (doesn't have an app or anything like that). You'd activate it from your existing bank's app. For example, the KBC app has a Wero icon you can use to enable payments via the system.

But generally I agree it's not an ideal situation and I fully blame Apple for the current state of things - all QR-code based systems (payconiq, Bancontact, etc.) could've been avoided if apps could provide payments and access NFC from the start but here we are.