No, the users must have a password. In this scenario, where you know the users do not have a password, you can just set a secure random password. A UUID, or other securely generated high entropy value.
You can provide the password value, but this will cause FusionAuth to hash it inline, so it will be costly in terms of time and CPU if you are importing a large number of users.
If you don’t want to take this hit at import time, you can provide these users just random hashed values, as long as you provide the factor, encryptionScheme, salt and password FusionAuth will assume this is a hash, and it will not re-hash it.