If you believe that you won't be needing a spare pump for a good while, it might be useful to consider having a set of spares offsite. For example, Leybold maintains a refurbished pool of pumps consisting of some of the most common models so they can send one out to customers within 24 - 48 hours.
However, the pool may not have the model you need in stock, and even if your pump provider has the pump you're looking for, you may still have multiple days of downtime. It might take a few days to arrive at your facilities.
Another option is taking advantage of your pump provider's strategic pool. This is when your provider will keep a specific set of spares especially for you, with a guarantee of it being in stock when you need it and shipped within 24 - 48 hours. Again, it might still take a few days to arrive at your facilities. There may be a small monthly holding fee, but your provider will be sure to have the pump(s) you need in stock.
The upside of this approach is that you do not have to pay for a spare pump until you need it, but the downside is that you have to wait for some time to have the pump delivered to you.